This invention relates to railroad cars. More specifically, this invention relates to the wheel and axles of railroad cars
Wheelsets for railroad cars are usually comprised of a one-piece axle and two wheels. The wheels are pressed onto the axle shaft and are rigidly mounted so that both wheels move exactly the same degree of rotation during operation. In some wheelsets the tread of the wheels is tapered to a larger diameter near the inside flange of the wheel. This tapering of the wheel treads allows a limited amount of relief from the wear and tear of the rigidly mounted wheels on the axle shaft but not enough to fully accommodate the adverse action of the rigid mounting. The conventional wheelset may be supported by journal bearings located outboard of each rigidly mounted wheel or the journal bearings may be located inboard of each rigidly mounted wheel. The rigid mounting of the wheels on the axle and the lack of independent rotation of these rigidly mounted wheels is the cause of slippage on the rail when the wheelset operates on curved sections of track. This slippage causes wear on the wheel treads and is a prime cause of corrective maintenance on both the wheels and the track.
Efforts have been made to overcome the problems associated with the rigid assembly of conventional wheelsets by placing a bearing or bearings between the axle and the wheel on at least one end of the axle to permit differential speeds of rotation on the wheels at opposite ends of the axle. In such cases, a hub is located on at least one end of the axle and a wheel is mounted on the hub or on the axle and its rotation with respect to the axle is facilitated by a bearing assembly.
To allow the operation of signaling systems, electrical continuity is necessary from the rails and through the wheels and the axle. When one of the wheels was mounted on the axle with a bearing assembly, the electrical continuity was sometimes less than perfect. If non-metallic bearings were used the electrical continuity was not possible.
In some cases, the problems associated with the rigid assembly of conventional wheelsets was addressed by providing mechanical mechanisms which could prevent independent wheel rotation one direction and allow rotation in the opposite direction. While such mechanisms could be provided with a certain degree of reliability by judicious design and material selection, the idea of incorporating a number of moving parts into the wheelset was not one that was attractive from a maintenance standpoint.
In other cases, the problems associated with the rigid assembly of conventional wheelsets were addressed by providing both outboard and inboard support members on the truck frame to support outboard and inboard bearings. In such cases, the bearings could be derated from standard sizes for a reduction in weight; however, the total weight of these special truck frames and the additional bearings added a considerable amount of additional weight to the railcar. In addition, in some applications, the inboard bearings or the bearing support arms would interfere with the railroad car frame when operating on curved track.
It is therefore a principal object of this invention to provide a railroad car wheelset with independent rotation of the wheels with respect to each other which will consistently retain the electrical continuity between the opposite wheels and the rails upon which they are supported.
A further object of this invention is to provide a wheelset with independent rotation of the wheels with respect to each other which can be used in existing railroad truck designs without modification to the truck structures or the braking systems.
A still further object of this invention is to provide a railroad wheelset which requires no additional maintenance than conventional wheelsets after installation and during service.
A still further object of this invention is to provide a railroad wheelset with independently rotating wheels in which the differential action is made available with no decrease in safety or reliability.
A still further object of this invention is to provide a railroad car wheelset with independent wheel rotation which can be economically manufactured and applied to railroad cars of all types.
A still further object of this invention is to provide a railroad car wheelset with independent wheel rotation wherein the bearings for the independent rotation system are comprised of a lubricating coating.
A still further object of this invention is to provide a railroad car wheelset in which the wheels can be mounted in substantially the same manner as in conventional wheelsets.
A still further object of this invention is to provide a railroad car wheelset with independent rotating wheels in which the independent rotating wheel action can be locked out during shipment or installation in the truck frame to prevent accidental rotation of the wheelset about the vertical centerline of the axle, and unlocked after the installation in the truck frame for the differential action.
A still further object of this invention is to provide a railroad car wheelset with independent rotating wheels in which the independent rotating wheel action on each axle can be selectively locked in or locked out to provide different operating characteristics to meet uni-directional or bi-directional car movements.
These and other objective will be apparent to those skilled in the art.